The present invention relates to devices and systems for the treatment of raw fluid containing various types of contaminants. More specifically, the invention relates to devices and systems for use in wastewater treatment methods that include aeration and settling phases.
Purification of fluids, such as wastewater, is often accomplished in a treatment system that utilizes two separate phases: aeration and settling phases. In the aeration phase, a gas, such as air or oxygen, is passed through the raw fluid to allow biological elements, such as bacteria, to act on the fluid matter contained therein. Following the aeration phase, the fluid enters a settling phase where sludge is allowed to settle out of the fluid. Also during the settling phase, remaining solid matter may rise to the surface as a floatation scum or sludge. This is typically removed by suction or mechanical means.
In conventional wastewater treatment systems, the sludge is typically removed by mechanical action on the water. For example, U.S. Pat. No. 5,454,942 to Ljungberg describes a reciprocating carriage apparatus that utilizes skimmer blades to mechanically force sludge from the surface of a treated fluid into a receptacle for subsequent removal. The various prior art devices, including the carriage device mentioned above, are not desirable because they typically contain moving elements that may be affected by exposure to sludge.
Another defect of the prior art is that conventional fluid treatment systems frequently rely only on gravity and a mechanical apparatus to remove sludge from treated fluid. This sometimes proves inadequate, and treated fluid can leave a treatment system with residual solids.
As a result of these and other defects of the prior art, there is a need for a skimmer device that enables simple and efficient removal of solid matter, such as sludge from treated fluids. Further, there is a need for a fluid treatment system that includes such a skimmer, as well as other structural elements that facilitate the removal of solid matter from treated fluid.
The present invention provides a fluid surface skimmer device and a fluid treatment system that utilizes the skimmer device. When used in a treatment system, the skimmer provides a further opportunity to remove solid material from the treated fluid.
The skimmer has self-adjusting properties that allow for optimum orientation of the skimmer no matter the orientation of the overall system. For example, if the tanks of a treatment system are installed such that they are not level, the skimmer adjusts its orientation to ensure proper alignment with the fluid surface within the treatment system. This allows the skimmer and treatment system to operate effectively in situations in which conventional devices and systems cannot.
In one embodiment, the skimmer comprises intake and outlet passages. The intake passage has a first passageway which defines an intake opening and a second passageway in fluid communication with the outlet passage. A flexible coupling connects the first and second passageways. Together, the first passageway, flexible coupling, and second passageway define a conduit that comprises the intake passage.
A collar is disposed on an exterior surface of the first passageway near the intake opening. Also, at least one buoyant member is attached to the collar. The flexible coupling allows for lateral and vertical movement of the first passageway relative to the second passageway, thereby allowing the skimmer to self-adjust by placing the intake opening of the first passageway at or near the fluid level.
The present invention also provides an improved fluid treatment system. The system is compact and efficient making it ideal for wastewater treatment applications, such as residential and agricultural wastewater treatment. The structural elements of the treatment system provide multiple opportunities to encourage settling of solid material out of the treated fluid. In a preferred embodiment, the system comprises a settling tank defining a first interior chamber and an aeration tank disposed within the first interior chamber. The aeration tank defines a second interior chamber. A base is disposed below the aeration tank and defines a communicative passageway between the first and second interior chambers.
A clearance exists between the exterior surface of the aeration tank and the interior surface of the settling tank. A plurality of vertically oriented brackets are disposed in the clearance and connect the aeration and settling tanks. The brackets provide a baffle that encourages further settling of solid matter out of the fluid.
A raw fluid inlet provides fluid access to the second interior chamber, i.e. the aeration tank, and a treated fluid outlet provides egress from the first interior chamber, i.e., the settling tank. A fluid surface skimmer according to the present invention is disposed in the clearance between the aeration and settling tanks. The intake passageway of the skimmer is disposed in the clearance and the outlet passageway is in communication with the second interior chamber. In this configuration, the skimmer removes fluid from the surface of the fluid in the clearance and returns the removed fluid to the aeration tank. Since the removed fluid is concentrated at the surface prior to removal by the skimmer, it is likely to contain flotation sludge if any is present. Accordingly, the skimmer acts to return flotation sludge to the aeration tank for further treatment by the system.
Preferably, a gas supply line has a first portion that extends into the second interior chamber and a second portion attached to a gas inlet of the skimmer. This allows a single gas supply line to drive the aeration and the skimmer.
While the invention is defined by the claims appended hereto, additional understanding of the invention can be obtained by referencing the following detailed description of preferred embodiments and the appended drawings.